Techniques have been developed in our laboratory to measure 1)the electrical activity of intrinsic laryngeal muscles, 2)laryngeal airway resistance and 3) glottic aperture size in human subjects. These techniques are used to determine laryngeal function during respiration in wakefulness and sleep. The overall goal is to determine 1)the physiologic and pathophysiologic factors that control the respiratory-related activity of intrinsic laryngeal muscles, and 2) the net effect of changes in intrinsic laryngeal muscle activity on the larynx.